Corn: Northern Corn Leaf Blight (Setospaeria turcica)

Excerpt from Chapter 1, Field Crop Protection Guide, Order this publication

Table of Contents

1. Description
2. Integrated Pest Management Options
   • azoxystrobin + propiconazole – Quilt
   • propiconazole – Tilt 250 E, Bumper 418 EC
3. Related links...

Description

The disease appears as long, elliptical (2-15 cm (1-6 in.)) greyish-green or tan streaks. Lesions most often begin on the lower leaves. As the disease develops, individual lesions may join, forming large blighted areas. In some cases the entire leaves may become blighted or "burned." Losses due to northern leaf blight are most severe when the leaves above the ear are infected at or slightly after pollination. The disease is often confused with Stewart's wilt.

Image 1. Northern corn leaf blight showing long elliptical greyish-green or tan streaks.

Integrated Pest Management Options

Incidence of this disease is on the rise in Ontario. Not generally a problem in field corn, since good resistance available. Seed corn may need protection. Crop rotation and tillage will reduce inoculum levels in surface residues. In reduced tillage systems, rotation and resistance are necessary. Chemical control not usually economical in field corn.

Comments
Ground and aerial application. Apply when disease first appears, followed by a second application 14 days after the first, if environmental conditions are favourable for disease development. Do not apply to field corn or field corn grown for seed after brown silk. 30 days to harvest for forage. 14 days to harvest for sweet corn. Maximum 2 applications per season.

Comments
Ground and aerial application. Apply when disease first appears. Can be tank-mixed with Ripcord or Matador insecticide for insect and disease control. 14 days to harvest.

Related links...

• Agronomy Guide for Field Crops - Publication 811
  • Corn: Northern Corn Leaf Blight
• Disease
• Corn